Conventional FM wireless receivers which utilize direct conversion architectures to detect I (in phase) and Q (quadrature phase) components of a received signal can experience non-optimal performance. Firstly, such receivers can develop errors in relative phase and amplitude between the I and Q components. The error in relative phase, herein referred to as ‘phase error’ and the error in relative amplitude, herein referred to as ‘amplitude error’, are sometimes referred to collectively as ‘quadrature imbalance’ errors. Furthermore, the receiver hardware can introduce into each of the I and Q components direct current (DC) offset errors. For example, such errors can be caused by radiation produced by local oscillators used in frequency downconversion and by imbalances in amplifiers of the receiver. All of these errors can contribute to distortion in a resulting output signal, e.g. an audio signal, produced by the receiver. The distortion may be unacceptable to users.
Procedures are known in the prior art for estimating the various errors in the I and Q components referred to earlier. It has been found that these procedures may be inaccurate under certain conditions. Furthermore, the known procedures may be dependent on modulation characteristics of the received FM signal or on a need to detect and correct for any frequency offset error between the carrier frequency of the received signal and the frequency of a local oscillator signal applied to obtain the signal. These dependencies can increase processing complexity in the receiver.